As the need for energy is increased recently, development on a solar cell that converts solar energy into electrical energy is in progress.
Especially, a Copper Indium Gallium Selenide (CIGS) based solar cell, i.e., a pn-hetero junction device having a substrate structure including a glass substrate, a metallic back electrode layer, a p-type CIGS based light absorbing layer, a high resistance buffer layer, and an n-type window layer, is widely being used nowadays.
A variety of research is being conducted on a barrier layer which can prevent impurity diffusion in a substrate of the solar cells.